Effects of body weight and feed allocation during sexual maturation in broiler breeder hens. 2. Ovarian morphology and plasma hormone profiles

Abstract

The effects of broiler breeder BW and nutrient intake on ovary morphology and plasma reproductive hormone profiles were examined at photostimulation (PS) (21 wk) and at sexual maturity (SM) in standard (STD) and low (LOW), or high (HIGH) BW birds provided either restricted (RF) or ad libitum (AL) access to feed between PS and SM. At PS, 30 Shaver Starbro pullets at target BW were assigned to the STD treatment, and birds either 20% heavier (HIGH) or lighter (LOW) assigned accordingly. Ten birds of each size group were processed immediately for carcass analysis and 10 birds assigned to each size by feed interaction group. Blood samples were taken at 3-d intervals beginning at PS and profiles constructed for estradiol-17beta, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) to examine the relationship between body size, feeding level, and reproduction. Birds were processed for assessment of reproductive traits following SM. The AL birds reached SM with 11.0 large yellow follicles (LYF) (> 10 mm diameter) compared to 7.1 in RF birds. Small follicle atresia (< 5 mm diameter) was low in AL birds (10.3) compared to RF birds (32.3). The extent of small follicle atresia in RF birds was found to be inversely proportional to LYF number by stepwise regression. Increased small follicle atresia was associated with a longer sexual maturation period in RF birds (r = 0.619; P = 0.0003). Plasma estradiol-17beta concentration was greater in HIGH than in STD or LOW birds at PS, suggesting more advanced ovary development in HIGH birds. Estradiol-17beta profiles were similar in shape in all treatments, with the primary difference being the length of time prior to a substantial estradiol-17beta increase. Following PS, plasma LH and FSH concentrations of AL birds increased to levels nearly double that of RF birds, indicating a role for nutrient intake with rate of reproductive development. Plasma LH and FSH concentrations remained elevated for a greater time period in RF birds, however, possibly relating to the development of processes limiting LYF recruitment. This experiment demonstrated a modulation of reproductive hormone concentrations during sexual maturation by feeding level in conjunction with a sensitivity of the ovary to nutritional effects.

Expression of anti-Mullerian hormone in hens selected for different ovulation rates

“…When allowed to eat ad libitum, these chickens become very fat and have excessive ovarian follicular development that often results in erratic ovulations (Yu et al 1992). This ovarian overgrowth can be somewhat controlled by RF (Yu et al 1992, Renema et al 1999, 2001) which improves egg production by enhancing dominant follicle selection but follicle development is still not as precise as that in laying hens. Feeding level in broiler breeder hens is not associated with any difference in basal or surge amplitude of plasma LH or progesterone or mean level of plasma E 2 (Liu et al 2004).…”

“…Eggs are laid at inappropriate times and eggshell quality is often poor (Yu et al 1992). This ovarian overgrowth can be somewhat controlled by restricted feeding (RF) which slows the rate of follicle growth and therefore, improves egg quality and production (Renema et al 1999(Renema et al , 2001). The average production rate of RF broiler breeder hens is w180 eggs per production cycle as compared with 250 eggs per production cycle for laying hens.…”

Influence of feed form and energy concentration of the rearing phase diets on productivity, digestive tract development and body measurements of brown-egg laying hens fed diets varying in energy concentration from 17 to 46 wk of age

“…In general, pullets that are heavier at 17 wk of age anticipate sexual maturity and egg production and lay larger eggs than pullets that are lighter (Renema et al, 1999a;Pérez-Bonilla et al, 2012b). In this respect, Summers et al (1987) and Renema et al (1999b) reported a positive relation between BW of the hens and the maturation of the reproductive traits and the onset of egg production.…”

Exigência De Metionina + Cistina Para Frangas De Reposição Na Fase Inicial (1 a 6 Semanas De Idade)

“…Isto ocorre porque os fatores que interferem na idade da ave à maturidade sexual estão diretamente relacionados com o peso corporal e a uniformidade do lote na fase de recria, sendo que existe alta correlação do peso da ave com seis semanas de idade e a idade em que a ave atinge a maturidade sexual. Renema et al (1) verificaram que o peso do ovário e do oviduto correlaciona-se com o peso corporal da fêmea, evidenciando o efeito do tamanho corporal sobre o desenvolvimento reprodutivo.…”